10-15 seconds after i stop the engine, it starts whinning and making these weird noises.
I never bothered to take it back to dealer to address the issue. Waiting for my service time to come up so they can address the issue.

The sound is like, a little fan constantly running somewhere inside a closed area right above the exhaust manifold or in the area where catalytic converter is located(if the diesel has one).

My "d" did the very same thing.The whirring noise you hear is the fan cooling the anti-freeze.Noises like that are normal.